The present world context regarding the exploitation of an electrical energy transmission network is the following: ageing components, increasing demand for energy, deregulation and opening of markets, increasing pressure from clients for quality and reliable energy. The electrical utilities are therefore required to know precisely the state of their transmission network in order to apply the principles of preventive maintenance for safekeeping the reliability of the systems. The state of a component is evaluated, inter alia, through measurements by means of sensors. With regard to the gathering of information, numerous sensors have been developed but the positioning of these sensors, in order to access the components, often remains an important challenge. The use of remote-controlled vehicles (ROV) for this task in order to achieve the inspection of circuits of conductors is therefore very appropriate.
Many vehicles of the ROV type have been developed in the past. A quick overview will bring forward the characteristics and disadvantages of the main ones.
Known in the art, there is a remote-controlled line chariot for the inspection of circuits with a simple conductor and which is the object of U.S. Pat. No. 6,494,141 (MONTAMBAULT et al.). This remote-controlled vehicle is very efficient, compact, relatively light and easy to use. It also has a good traction force which renders it very versatile. It is a third generation prototype that has proven many times over its efficiency, its mechanical robustness and its robustness to work under live electrical conditions (315 kV, 1000 A). It allows the de-icing of overhead ground wires and of conductors, thermographic and visual inspections and the measurement of the electrical resistance of sleeves. It travels on simple conductors regardless of their diameters. However, even if this type of ROV is capable to pass over mid-span jointing sleeves, it cannot pass over on its own pylons, vibration dampers or spacers. It has to be removed when it reaches an insurmountable obstacle and has to be mounted back again on the other side of the obstacle.
Also known in the art, there exists the international patent application published under no. WO 2004/070902 A1 (POULIOT et al.) that discloses a remote-controlled vehicle having temporary support rotors that allow it to clear obstacles of greater dimensions than the previous one. However, this vehicle cannot clear certain large obstacles such as aerial warning markers that are mounted on certain conductors, on pylons or other diverse objects encountered on the conductive cables.
There exist other vehicles that specifically aim to solve the problem of clearing pylons. Indeed, hereinbelow, there are described a few experimental prototypes that clear obstacles on simple conductors.
An example of a remote-controlled vehicle that can clear obstacles is known under the name of NSI Power Line Inspection System. This vehicle was developed together with NASA. This vehicle travels on the conductor and can clear objects in the manner of a caterpillar. This vehicle aims mainly to provide visual inspection, but also the addition of sensors of all sorts for the inspection of all the components of the line.
FIG. 1 shows a vehicle that is known under the name of TVA Line ROVER. This vehicle was developed by the Tennessee Valley Authority Society at the beginning of the 1990's, in order to inspect power lines. This vehicle travels on the conductor and can clear certain obstacles thanks to arms that allow it to move temporarily in the manner of a spider.
FIG. 2 shows a vehicle designed by SAWADA et al. It is a line robot that is quite complex and that is able to clear obstacles such as insulator strings and vibration dampers. This vehicle also aims the visual inspection and the diagnostic of line components. There are more details provided about this type of vehicle in U.S. Pat. No. 5,103,739 (SAWADA et al.).
These last three vehicles are relatively large, heavy, cumbersome, complex and difficult to install. It is not clear to know if these are capable to work under live electrical conditions. The configuration of these vehicles tends to make them susceptible to stability and fragility problems.
As mentioned above, power transmission networks include a large variety of components that would be advantageous to be able to clear with a remote-controlled vehicle of the ROV type.
There is therefore a need in this field for a remote-controlled vehicle intended to be mounted on a cable, which would be relatively compact and would be less susceptible to stability and fragility problems of the vehicles known in the art and that could be able to clear, in a relatively short time, a large variety of obstacles that are found on the cables of the power transmission networks.